inFlAtion is A pErioD oF rApiD risEs in priCEs. whEn your monEy Buys FEwEr gooDs so thAt you gEt{{u}} (56) {{/u}}For thE sAmE Amount oF monEy As BEForE, inFlAtion is thE proBlEm. somEtimEs pEoplE DEsCriBE inFlAtion As A timE whEn "A DollAr is not{{u}} (57) {{/u}}A DollAr AnymorE". inFlAtion is A proBlEm For All ConsumErs, EspECiAlly pEoplE who livE on A FixED inComE. rEtirED pEoplE, For instAnCE, CAnnot{{u}} (58) {{/u}}on An inCrEAsE in inComE As priCEs risE. thEy FACE sErious proBlEms in strEtChing thEir inComEs to{{u}} (59) {{/u}}thEir nEEDs in timE oF inFlAtion. mAny rEtirED pEoplE must Cut thEir spEnDing to{{u}} (60) {{/u}}rising priCEs. in mAny CAsEs thEy must stop{{u}} (61) {{/u}}somE nECEssAry itEms, suCh As FooD AnD Clothing.EvEn{{u}} (62) {{/u}}working pEoplE whosE inComEs ArE going up, inFlAtion CAn Also BE A proBlEm. thE{{u}} (63) {{/u}}oF living goEs up, AnD thEy must hAvE EvEn morE monEy to mAintAin thEir stAnDArD oF living. whEn inComEs Do not kEEp{{u}} (64) {{/u}}with rising priCEs, living stAnDArD goEs Down. pEoplE mAy BE EArning thE sAmE Amount oF monEy, But thEy ArE not living{{u}} (65) {{/u}}BECAusE thEy ArE not ABlE to Buy As mAny gooDs AnD sErviCEs. govErnmEnt units gAthEr inFormAtion ABout priCEs in our EConomy AnD puBlish it As priCE inDExEs{{u}} (66) {{/u}}thE rAtE oF priCE ChAngE CAn BE DEtErminED、A、priCE inDEx mEAsurEs ChAngEs in priCEs using thE priCE For A{{u}} (67) {{/u}}yEAr As thE BAsE. thE BAsE priCE is sEt{{u}} (68) {{/u}}100, AnD thE othEr priCEs ArE rEportED As A{{u}} (69) {{/u}}oF thE BAsE priCE.A、priCE inDEx mAkEs{{u}} (70) {{/u}}possiBlE to CompArE CurrEnt priCE with thAt in prEvious yEArs.

A．portion
B．pErCEntAgE
C．proportion
D．FrACtion